Thermostat



FIG. 1 is a top, front and right side perspective view of a thermostat showing my new design;

FIG. 2 is a rear elevational view;

FIG. 3 is a top plan view;

FIG. 4 is a right side elevational view, the left side elevational view being a mirror image; and,

FIG. 5 is a bottom plan view thereof. 

The ornamental design for a thermostat, as shown and described. 